From 20b8961640b6c22d4149f7268d403cb4609a03fb Mon Sep 17 00:00:00 2001
From: Elias Fleckenstein <eliasfleckenstein@web.de>
Date: Sun, 7 Jun 2020 18:34:21 +0200
Subject: New file Structure

---
 src/common/random.lua | 40 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 src/common/random.lua

(limited to 'src/common/random.lua')

diff --git a/src/common/random.lua b/src/common/random.lua
new file mode 100644
index 0000000..4fbbed3
--- /dev/null
+++ b/src/common/random.lua
@@ -0,0 +1,40 @@
+skycraft.random = {
+    choices = {},
+    probabilities = {},
+    csum = {},
+    sum = 0
+}
+
+skycraft.random.__index = skycraft.random
+
+function skycraft.random:new(o)
+    o = o or {}
+    setmetatable(o, self)
+    o.choices = {}
+    o.probabilities = {}
+    o.csum = {}
+    o.sum = 0
+    return o
+end
+
+function skycraft.random:calc_csum()
+	self.sum = 0
+    for i, choice in ipairs(self.choices) do
+        self.sum = self.sum + self.probabilities[choice]
+        self.csum[choice] = self.sum
+    end
+end
+
+function skycraft.random:choose()
+    local r = math.random() + math.random(0, self.sum - 1)
+    for i, choice in pairs(self.choices) do
+        if r < self.csum[choice] then
+            return choice
+        end
+    end
+end
+
+function skycraft.random:add_choice(choice, probability)
+    table.insert(self.choices, choice)
+    self.probabilities[choice] = probability
+end 
-- 
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